Doctors and surgeons traditionally used optical systems to visualize surgical fields on and in the body. Although a surgeon may perform many procedures with the naked eye, a number of procedures often require magnified images of the surgical field for the surgeon to operate. It is known to magnify images of a surgical field to obtain a detailed view upon which the surgeon may reference while performing an operation or examination. Surgical procedures using image magnification techniques to view a surgical field are referred to as microsurgery. Microsurgery is commonly used in neurosurgery, including brain and spinal surgeries performed by neurosurgeons and orthopedic surgeons. Another use of microsurgery is anastomosis, or artificial connection, of blood vessels and nerves which are usually 1 mm in diameter or smaller. Further examples of microsurgery include procedures by otolaryngologists on the inner ear, and the vocal chords, and procedures by urologist and gynecologists to reverse vasectomies or tubal ligations.
The surgical microscope is a known device used to obtain magnified views of a surgical field visible from outside the body. The surgical microscope allows a surgeon to observe a magnified image of the surgical field visible from outside the body. Microscopes of this type use an optical lens system for receiving, magnifying, and displaying an optical image of the surgical field. The surgical microscope includes a monocular or binocular with relatively small pupils for viewing the images. Most surgical microscopes further include a second monocular or binocular and a means of splitting the optical beam to provide a surgeon's assistant with a means to view the image. Known surgical microscopes further include an optical globe or flexible light cable connected to an external light source for illuminating the surgical field visible from outside the body.
Although the surgical microscope allows a surgeon to observe magnified images of a surgical field visible from outside the body, the surgical microscope has many drawbacks and disadvantages.
A disadvantage of the surgical microscope is its relatively large size. The surgical microscope is a large device that must be supported over the surgical field on a stand adjacent to the operating table. The size of the surgical microscope limits the working space around the operating table. The microscope must further be cantilevered on its stand with a cumbersome counterbalance the microscope over the surgical field. Moreover, a dedicated assistant is required to operate the surgical microscope and maintain the surgical microscope, prior to, during, and after a surgery. Further, the surgical microscope is not part of the sterile field, and must be draped prior to use, and undraped after use thus increasing maintenance time, costs, and constraints on mobility.
Another disadvantage of the surgical microscope is that the surgeon and/or assistant must peer through binocular pupils to view the magnified images of the surgical field. Constantly looking into the pupils causes fatigue in the surgeon and assistant who use the microscope because they must maintain their eyes in close proximity of the viewing pupils for extended periods of time. This requirement also causes fatigue because the surgeon and assistant must lean over the operating table to look into the pupils, while at the same time performing the surgery below. As mentioned above, many surgical microscopes include multiple sets of binoculars to allow multiple users to simultaneously view magnified images of the surgical field. Multiple view ports reduce image intensity by factor equal to the number of binoculars, because a beam splitter is used to split the received optical image and direct it to each set of binoculars.
Another disadvantage of the surgical microscope is that is has an extremely shallow depth of field, approximately 1-2 mm. This limitation means that the microscope can only maintain a focus depth of about 1 mm in front of the focal point and a depth of about 1 mm past the focal point. 1-2 mm is not a sufficient depth of field to perform many microsurgical procedures without adjusting the focus during the procedure. To properly view the full surgical field the surgeon or her assistant must continually refocus the microscope to maintain the surgical field in focus.
Another disadvantage of the surgical microscope is that it requires a high intensity light source to provide images. The surgical microscope may either include an optical globe or flexible light source connected to an external source of illumination to produce the necessary light intensity. The light source increases the weight and size of the surgical microscope.
Another disadvantage of the surgical microscope is its cost. A new surgical microscope costs approximately between $230,000 and $250,000. Once purchased, the surgical microscope further requires a dedicated technician to operate, position, and maintain. The microscope additionally requires a very large storage area in or around the operating room. This is increasingly a disadvantage in today's operating rooms as the amount and size of surgical equipment continues to increase, while storage space in and around the operating room decreases.
One device that has been developed to overcome the disadvantages of the surgical microscope described above is U.S. Pat. No. 4,987,488 to Berci. The '488 patent discloses a video system for visualizing a surgical field with an enhanced depth of field. This disclosure relates to an improved system for viewing and magnifying images of the surgical field. The system uses a variable focal zoom lens connected to a high resolution video camera. The camera is further connected to a means of displaying images of the surgical field in the operating room such as a video monitor mounted above the operating table.
A possible disadvantage of the video system disclosed in the '488 patent is that a specific camera, namely a high resolution color video camera with a particular sensor area, is required. Therefore, interchanging another camera with the higher resolution camera disclosed in the '488 patent may not be possible.
In addition, camera control units (“CCU”) are typically compatible with a limited number of camera heads. A CCU's hardware is usually difficult to configure for proper communication with varying types of camera heads because camera heads use varying types of imaging devices that can differ in pixel resolution, timing requirements (i.e. PAL, NTSC, Progressive, and other formats), signal output type (i.e. analog or digital), physical size, and in other characteristics. Since the CCU is typically compatible with a select number of camera heads, changing the camera head usually means the CCU needs to be changed as well, and vice versa.
A further disadvantage of the video system is that the hospital operating room staff must store and maintain the new lens and the new camera. This requirement further increases the cost of the video system. The hospital must develop and put into place procedures for maintaining the new equipment, and then train staff to follow those procedures. The hospital must further dedicate a storage area for the equipment in an already crowded operating room.
Another optical system for inspecting the body is endoscopy, where surgeons can view and operate on a surgical field not visible from outside the body, for example on the stomach of the uterus. An endoscope is typically a long slender device using fiber optics and powerful (ROD) lens systems to provide lighting and visualization of the interior of a body. A portion of the endoscope inserted into a small incision in the body to receive optical images of a surgical field not visible from outside the body.
Another disadvantage of the video system is that is does not utilize existing operating room equipment to visualize a surgical field from outside the body, but rather requires an additional expense for equipment dedicated to a single task.
In FIG. 1, a prior art video system for receiving images not visible from outside the body is shown. The system comprises a telescope lens connected to an endoscopic camera head. The distal end of the telescope lens is inserted into an incision in the body and receives images of surgical field not visible from outside the body. Generally, the distal, image receiving end, of the telescope lens is adjacent or in close proximity to the surgical field, and provides little magnification.
As a result of the increase in endoscopic procedures, many operating rooms are equipped with an assortment of equipment to perform such endoscopic procedures. For example, most hospitals already own one or more endoscopic camera heads for coupling with a telescope lens and receiving images not visible from outside the body. The endoscopic camera head is designed to detachably couple with endoscopic lenses to obtain images from inside the body. Another example of a widely used endoscopic tool is the camera control unit which connects to the endoscopic camera head. Camera control units are designed to work with specific camera heads. Hospitals that own one or more endoscopic camera head also own the associated camera control units for operating the camera control heads.
In general, all or most of a hospital's endoscopic cameras are compatible with all of the associated camera control units because manufactures of a specific brand strive to provide compatibility in their product lines. Hospitals tend to purchase a portion of their endoscopic equipment from one supplier or manufacturer as the surgeon's and administrators become comfortable with a brand. Therefore because one of a plurality of camera control heads is compatible with one of a plurality of camera control units, the there is a great deal of flexibility the use of surgical equipment. It is therefore desired to be able to use one of a plurality of camera heads to connect to a microsurgery lens, and connect the one of a plurality of camera heads to one of a plurality of camera control units.
Moreover, many operating rooms are increasingly equipped with high definition audio video equipment to interface with the endoscopic equipment. For example operating rooms designed for endoscopic procedures include high definition monitors for viewing the surgery. The operating rooms further include computer equipment for receiving, monitoring, and distributing signals obtained from the endoscopic equipment.
What is desired therefore is a procedure that permits viewing of an object in a field of view while overcoming the disadvantages of the surgical microscope and the '488 patent. Another desire is a procedure that permits viewing of the object in the field of view in a simplified manner.